The mq-deadline I/O scheduler is more stable than BFQ. Additionally, the
boot time is shorter with the mq-deadline I/O scheduler. It only changes the scheduler on new kernel.
Bug: 186902601
Test: forrest build
Change-Id: I9433d73e7ed4bfd5e72a0f8318e959373e76202e
Signed-off-by: Ocean Chen <oceanchen@google.com>